The present application relates to a battery and a method for producing the same. Specifically, the present application relates to a battery in which a battery element is sealed with an outer package.
Battery packs that use a laminate film or the like as an outer package have been widely used because they are lightweight and have high energy density. Such battery packs are produced by housing, in an outer package, a battery element including a positive electrode, a negative electrode, and a separator, injecting an electrolytic solution into the outer package, and injecting and impregnating the electrolytic solution into the battery element.
For example, the following method is disclosed as a method for producing a battery pack, the method including such an injection and impregnation step (refer to Japanese Unexamined Patent Application Publication No. 2000-311661).
First, a battery element is housed in an outer package including an opening portion whose shape and size are larger than necessary. The outer package that is housing the battery element is then disposed in a vacuum chamber so that the opening portion faces upward. Subsequently, an electrolytic solution is injected into the opening portion of the outer package under reduced pressure, and then the pressure in the vacuum chamber is returned to atmospheric pressure. Thus, the electrolytic solution injected into the opening portion of the outer package is injected and impregnated into the battery element through a space above the battery element, the space serving as a temporary pool. The outer package that is housing the battery element is then taken out of the vacuum chamber. A region that is on the opening portion side of the outer package and adjacent to the battery element is heat-sealed. An unnecessary portion of the opening portion of the outer package is cut out while the heat-sealed region is left.